Spinners look cool on a classic IMO, and that'* why I want to add them. It gives the wheel a distinct look. Spinners themselves used to cover up the center lugnut on "knock-off" wheels back in the day, but after that were just for looks and not function.
Pontiac offered spinners until 1967 (on hubcaps that look just like my 1969'*), and then they were discontinued because there was a big push in safety from auto manufacturers. Somebody thought spinners might fly off while the vehicle was moving, creating dangerous flying debris (seriously). But I want them on my '69.
I could get a set of factory PMD spinners from a '67 Bonneville or similar, but the ones in decent shape are too darn expensive... however the aftermarket set I got (pictured) look almost exactly the same, except for the lack of PMD centercap.
If I can't get them to fit securely, I won't use them... but I was hoping there'* a way. I'll take a photo of the back of the spinner later on and post it.